The Rim Fire near Yosemite National Park has burned through about 260,000 acres of forest and likely won't be contained until early October. Winter rain and snow should help fully extinguish the fire, but that moisture comes with its own set of problems.

When the winter rains start falling, the burn areas become prone to erosion, and all that ash could end up choking the area's pristine rivers. Todd Ellsworth is heading up a Forest Service team to try to prevent such a scenario.